The Meaning of Call 811 (Call Before You Dig)

Definition of Call 811 (Call Before You Dig)

Call 811 is the free national call-before-you-dig number in the United States. Calling 811, or submitting a request online, connects an excavator or homeowner to their state's one-call center. The center notifies the utility operators in the area, which then send locators to mark the approximate location of their buried lines with paint, flags or stakes before digging begins.

Underground utilities include natural gas lines, electrical cables, water and sewer pipes, telecommunications and fiber optic cables. Striking one can cause explosions, fires, electrocution, flooding, service outages and serious injuries. Contacting 811 before excavation is the first step in preventing these strikes on construction, landscaping, fencing, utility and demolition jobs, and it is also required by state law in all 50 states for most types of digging.

Regulations and Requirements

OSHA Excavation Rules

Under 29 CFR 1926.651(b), employers must determine the estimated location of underground utilities, such as sewer, telephone, fuel, electric and water lines, before opening an excavation. Utility companies or owners must be contacted within established or customary local response times and asked to locate their installations. If they cannot respond within 24 hours, unless state or local law sets a longer period, or cannot establish the exact location, the employer may proceed with caution using detection equipment or other acceptable means. When the excavation approaches the estimated location, the exact location must be determined by safe and acceptable means, and exposed utilities must be protected, supported or removed while the excavation is open.

State One-Call Laws

Each state has its own damage prevention law that sets the details, including:

• Notice time: How far ahead a request must be made, often two to three working days.
• Ticket life: How long a locate request stays valid before it must be renewed.
• Tolerance zone: The distance on each side of a mark where hand digging or other careful methods are required, commonly 18 to 24 inches depending on the state.
• Positive response: Many states require operators to confirm that lines have been marked or that they have no facilities in the area before digging starts.
• Penalties: Fines or liability for damage when excavators dig without a valid ticket.

Utility Marking Colors

Locators use the American Public Works Association uniform color code to show what type of utility is buried:

• Red: Electric power lines, cables and conduit.
• Yellow: Gas, oil, steam and other gaseous or flammable materials.
• Orange: Communication, alarm and signal lines, cables and conduit.
• Blue: Potable water.
• Purple: Reclaimed water, irrigation and slurry lines.
• Green: Sewers and drain lines.
• Pink: Temporary survey markings.
• White: Proposed excavation area, marked by the excavator before calling.

Good Practices for Safe Digging

• White-line the dig area: Mark the proposed excavation in white paint or flags so locators know exactly where you plan to work.
• Wait for all responses: Confirm every notified operator has marked or cleared the area before breaking ground.
• Remember private lines: 811 usually covers public utility lines. Service lines, site lighting, irrigation and other privately owned lines may need a private locator.
• Respect the tolerance zone: Hand dig or use vacuum excavation to expose lines within the tolerance zone, and pothole to confirm depth.
• Keep marks visible: Protect and refresh marks, and request a new locate if they are destroyed or the ticket expires.
• Plan for a strike: Make sure crews know what to do if a gas line is hit: stop work, move away, call 911 and the operator, and keep ignition sources away. Include this in your emergency action plan.

Example of Call 811 (Call Before You Dig)

A fencing contractor is installing a new perimeter fence around a commercial lot. Three working days before the job, the project manager white-lines the post locations and submits an 811 request. Locators mark a gas line in yellow and a fiber optic cable in orange that cross the planned fence line near the entrance.

On the first day of work, the crew lead confirms that all operators have responded and reviews the marks during the pre-task plan. Within the tolerance zone, the crew uses vacuum excavation to expose the gas line and confirms its depth before shifting two post holes a few feet to avoid it. Because the lot owner mentioned buried parking lot lighting, the contractor also hires a private locator, who finds an unmarked electrical feed that the crew avoids.

Frequently Asked Questions: Call 811 (Call Before You Dig)

Is calling 811 required by law?

Yes. Every state has a damage prevention law that requires excavators to notify the one-call center before most types of digging. Requirements and exemptions vary by state.

How long does it take to get lines marked after calling 811?

It depends on the state, but many require notice two to three working days before digging. Check your state one-call center for exact timelines.

Does 811 mark all underground lines?

No. Member utility operators mark their own lines, which usually stop at the meter or property line. Privately owned lines may need a private locating service.

What should I do if I hit a utility line?

Stop work immediately. If it is a gas line, leave the area, avoid ignition sources and call 911 and the utility operator. For any strike, notify the operator so the line can be inspected and repaired, even if damage seems minor.